Viper aims to deliver the sound characteristics of legendary hardware synthesizers in a virtual format. We can call Viper a Virtual Performance synth, with a vast array of features like: multiple oscillator types with user waveforms, Sync, Frequency Modulation, Ring Modulation, unison up to 8 voices, filter saturation, filter routings, mod matrix, high quality effects, a powerful arpeggiator, and much more!

A lot of time and research has been invested to make the sound engine of Viper capable of delivering a wide array of sounds, everything from smooth, lush pads, huge basses, and powerful leads, typically associated with traditional analog synthesizers. This was achieved with careful coding, experimenting, analysing hardware synths, and using the ear to fine tune the controls. A constant randomization is also active in the synth to slightly alter its sound to mimic electronic components.

The engine is written in optimised code to use as little CPU consumption as possible, while maintaining a high quality sound engine, finding a good balance between the two. The synth automatically turns off any parts that are not used to further reduce CPU usage. Viper also has a smoothing algorithm for its controls to remove the ‘steppyness’ when it goes between values to give that extra polished sound.

Key features:
● Classic Oscillators with user waveforms
● Multisaw (up to 9x Sawtooth waveform)
● Sub Oscillator
● Noise with coloring
● Punch
● Osc Sync, FM, RM
● Unison up to 8 voices
● 2 Zero Delay Feedback filters with Low Pass, High Pass, Band Pass, Band Reject (notch)
● Filter Saturation curves
● 4 Filter routings: Serial 4, Serial 6, Parallel, Split
● 4 Envelopes: Filter Env, Amp Env, Mod 3 and Mod 4
● 3 LFOs with Oscillator shape morphing
● Mod Matrix
● FX:
● Character (analog boost)
● Distortion
● Filter effects: Ring Modulator, Frequency Shifter, Vowel Filter, Comb Filter
● Phaser
● Chorus
● Delay
● Reverb
● Equalizer
● Arpeggiator with user patterns and Midi Out
● Built in Preset browser
● Section locking
● Midi learn
● Resizable GUI


Download demo version:
Demo restrictions: Preset saving is disabled, silence every 60 seconds. (Because of the demo limitations, automation is not available in some hosts, but is fully functional in the retail version)
Requirements: Win 32/64 compatible system with SSE2 (or higher).

User Manual:
The user manual for Viper can be downloaded from here: Viper Manual.pdf

This is a 32 & 64-bit VST for Windows only! All future updates are free!
Please evaluate the demo thoroughly before purchasing!

Why no Mac version?
Unfortunately, FlowStone does not yet support export to AU, Mac VST yet. As soon as FlowStone supports this, the synth will be available in this format.

Free Soundbanks:
Daniel Craighead Trance Access for Viper Vol.1.zip


  • Dave
    Nov 10, 2018

    Any Tasty Black Friday offers on the way? 🙂

    • tf
      Nov 10, 2018

      Interesting question… I would definitely buy such an offer and tell everyone.

      • Benjamin
        Nov 11, 2018


        • A2C
          Nov 15, 2018


    • Jonas
      Nov 18, 2018


      I would buy it instantly.

      • tf
        Nov 26, 2018

        was there an offer? did i miss it?

        • Adam Szabo
          Nov 26, 2018

          There was no offer now, there will be offers from next year 😉

  • Bill Burr
    Nov 19, 2018

    +1 yes yes yes

  • daxx
    Nov 20, 2018

    resize gui ? looks very small on my 4K…

    • Adam Szabo
      Nov 20, 2018

      The next update will have resizeable gui

  • Er
    Nov 23, 2018

    Any Black Friday sale?

    • kurratz
      Nov 25, 2018

      Friday is gone but Cyber Monday comes.

      • kurratz
        Nov 25, 2018

        p.s I am not from sweden 😉

  • Dalil
    Nov 25, 2018

    Kind of sad, no special offer in spite of black Friday 🙁 I understand it but I’m sad anyway…I’m waiting since the release for an offer…

    • kurratz
      Nov 25, 2018

      you are not alone. 50% and I’m in.

  • My name is Matt
    Nov 26, 2018

    I’m hoping some of his older soundsets go on sale. Come on Adam PLEASE!

  • barry
    Nov 27, 2018

    if you buy it will the updates always be free?

    • Adam Szabo
      Nov 28, 2018

      Yes all future updates are free

  • Joe R
    Nov 29, 2018

    Viper is my most used synth! Great presets and fun to play with.

  • George
    Dec 08, 2018

    Best sounding synth ive heard in a long time . Amazing job Adam. Is there more soundsets coming for this ?

    • Adam Szabo
      Dec 08, 2018

      Thank you! Yes there are tons of soundsets planned!

  • Armando Sousa
    Dec 11, 2018

    Hi, I really want to buy Viper, but I work with Mac and saw that there is no Mac installer. Why? When did you release the Mac version?



    • Adam Szabo
      Dec 11, 2018

      If you read on my website carefully, I explain that a Mac version is not possible because the platform in which I create Viper can only export to windows Vst. There is nothing I can do about that 🙁

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